Name: Helen

Message: I am making dog toys from hemp rope/canvas and also loofah which I would like to dye. I am concerned that the toys will be chewed and potentially eaten so want to find a safe non toxic dye that is colour fast and also eco friendly.  I was going to use natural vegetable dyes but the dyeing process seems very complicated and not necessarily safe! Please could you recommend a suitable dye that would be non toxic and as eco friendly as possible?

You can't use the safest class of dyes, which are the food colorings, because they will not work on cellulose fibers such as hemp or loofah. They will work only on nylon or on animal fibers, such as wool.

As you have seen, most natural dyes require mordants, which would not be suitable for dogs to chew on. The least toxic mordant is alum, but even that can be irritating and slightly toxic. (The fatal dose for an adult human is about one ounce.)

One natural dye that works well on plant fibers is turmeric. Unlike the majority of natural dyes, turmeric is a direct dye, which means that it will dye cellulose fibers with no mordant at all. The color produced is a bright orangish yellow. Turmeric is not a very good dye for clothing, because it tends to fade in the light, and in the laundry as well. It seems likely to me that neither of these will be a huge drawback for dog toys, which tend to have a fairly short lifespan. Turmeric is certainly worth your running some tests. Try simmering one dog toy for half an hour in a saucepan of water which covers the toy completely, with one to four tablespoons of ground dried turmeric mixed into the water. Adding a few spoonfuls of salt might be helpful. Look in the grocery store for ground turmeric; you'll probably find the prices dramatically cheaper if you can buy it in bulk rather than in tiny glass jars.

Walnut hulls will also produce a good direct dye for cellulose, but the dark brown color may not be much fun for dog toys. You must gather pounds of walnut hulls if you are going to dye with them.

Another good choice for dyeing cellulose fibers such as hemp and loofah would be fiber reactive dyes. These are considered to be more ecologically sound for use than other classes of synthetic dyes. As a general rule, fiber reactive dyes are not appreciably toxic if they have been fixed to the fiber properly, with soda ash, and all excess unattached dye has been washed out, using very hot water (140°F) after an initial cool rinse. However, none of the fiber reactive dyes have been tested for safety when eaten. The most popular fiber reactive dye is Procion MX dye. This is the same dye that is so popular for use in tie-dyeing clothing. The dye actually forms a permanent chemical bond with the fiber, which cannot be broken even by boiling. There is always quite a bit of unattached dye which must be washed out, but once you have done that, what's left is quite permanent. Dylon Machine Dye is a fiber reactive dye which would be worth your trying, if you can find it. For recipes, see How to Dye with Fiber Reactive Dye and Washing Machine Dyeing. To find a local source from which to mail-order fiber reactive dyes, see my page of Sources for Dyeing Supplies Around the World .

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[Updated January 14, 2009.]